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  <script>
    // 8. 将字符串"i come from beijing"倒置，即控制台输出"beijing from come i"
    // 语句直接写在程序中，不需要用户输入

    function reverseSentence (str) {
      if (typeof str !== 'string' || !str[str.indexOf(' ') - 1] || !str[str.indexOf(' ') + 1]) throw new Error('请输入一个句子')
      return str.split(' ').reverse().join(' ')
    }
    console.log('\"i come from beijing\"倒置，即控制台输出\"beijing from come i\"')
    console.log(reverseSentence('i come from beijing'))
  </script>
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